Figure 1
From: Tuning inter-dot tunnel coupling of an etched graphene double quantum dot by adjacent metal gates
Sample characterizaion.
(a). Scanning electron micrograph in false color of the device.Dark regions are the graphene base structure consisting of a double quantum dot (100 nm*100 nm for each dot, 35 nm*100 nm for each ribbon) and an integrated QPC channel serving as in situ charge detector. Grey area is the etched-away region that shows the SiO2 substrate surface. The yellow regions are the metal gates used for control and as source/drain electrodes. (b). A typical QPC charge sensor stability diagram of the double quantum dot: differential charge sensor current dIQPC/dVLP as a function of two gate voltages VLP and VRP. The structure shows a well-defined double quantum dot with characteristic honeycomb patterns. Charge state is defined by (M, N), where M and N are the electron number in the left and right dot, respectively (The charging energy and regularity are the same throughout the samples tested. The difference in the honeycomb size between Fig. 1b and the else in the article stems from doped and undoped sample substrates).
